Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered; the description adds real behavioral context by specifying the Exchange-server view and the returned fields (id, name, path, parent_id, counts). It stops short of stating the prerequisite that a connected M365 account must exist or what happens without one, so it isn't fully complete.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Three sentences, each doing work: purpose and return shape, downstream routing, and sibling differentiation. It is front-loaded with the trigger and has no filler.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the output schema exists and annotations cover the safety profile, the description supplies more than enough: scope, return fields, sibling exclusion, and downstream usage. Nothing needed to call it correctly is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Only one parameter and schema description coverage is 100%, so the schema already fully explains 'account' (UPN, id, display name, default fallback). The description adds nothing about the account parameter, so the baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb (list) and resource (mail folders of an M365/Outlook account as Exchange exposes them) with the exact fields returned. It explicitly contrasts with the sibling 'list_email_folders' for the Mac Mail app, so an agent can disambiguate without opening schemas.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Opens with an explicit 'Use this when...' trigger and names the alternative to use instead ('For the folders of an account in the Mac's Mail app, use list_email_folders'). It also routes downstream consumers (m365_list_emails, m365_search_emails, m365_create_email_folder, m365_move_email), which is genuine when-to-use guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.